Underwater missile



July 13, 1965 T. G. LANG UNDERWATER MISSILE Filed Feb. 13, 1961 IOFOEATTORNEY United States Patent() Navy Filed Feb. 13, 1961, Ser. No.89,075 2 Claims. (Cl. 114-20) (Granted under Title 3S, U.S. Code (1952),sec. 266) The invention described herein may be manufactured and used byor for the United States of America for governmental purposes Withoutthe payment of any royalties thereon or therefor.

This invention relates to underwater vehicles, such as torpedoes, andmore particularly to improvements in method and apparatus for propellingsame.

The ultimate in torpedo design is conceivably a vehicle which issubstantially all payload explosive with a propulsion and guidancesystem of substantially no weight or volume which would carry thepayload at any desired speed to any desired range. The obviousimpracticability of such vehicle has dictated a judicious compromisebetween its competing components and the art has been so highlydeveloped that designers of various components are almost invariablyrestricted to remain within their spacial and weight allotments withoutencroachment upon those of the others. The problem is furthercomplicated in thatlcertain components may be considered as fixed andothers as variable. Thus, if it is desired to deliver a predeterminedweight of explosive to a target, the explosive, guidance system, partsof the shell, certain structure and portions of the propulsive elementsrepresent volume and weight which is unaffected by range or speed.Variable components are those the volume of which is proportional topropulsive power such as the energy source, the major portion of thepower plant and certain other parts of the shell and structure. For along range high speed torpedo size reduction becomes cumulative. Thus,if the drag could be `decreased by a factor of 2 the displacement ofengine and fuel could be reduced about 50%. This reduction, however,would in some cases effect a reduction of about 40% Vin the wettedsurface area permitting a further reduction in the power plant byanother factor of nearly 1.5. The resulting reduction in horsepowerwould thus be a factor of the order of 3 which, aswill be apparent,would radically modify present torpedo design. For example, electricpropulsion could probably be employed for higher speeds and greaterrange than heretofore possible.

Analysis has revealed that at high speed with fully turbulent flow,changes in torpedo hull or fin shape cannot effect significant reductionin drag. Since substantially all of the torpedo power is utilized inovercoming drag and since efficiency and performance of power plants hasreached a near optimum state of development within allotted space itbecomes apparent that if further significant improvements are to bemade, radical and unconventional approaches will be required tomaterially reduce the drag of otherwise hydrodynamically well designedtorpedoes.

The principal object of this invention is to provide a novel torpedowhich significantly reduces drag as comdescription to follow, theappended claims and the accompanying drawing, in which:

FIG. l is a side elevation of a torpedo embodying the subject of theinvention;

FIG. 2 is an enlarged section taken on line 2 2, FIG. l, intermediateportions being omitted;

FIG. 2A is a hull section illustrating an undesired flow condition, FIG.2B is a like hull section illustrating correction of the lundesired flowcondition;

FIG. 3 is a section taken on line 3 3, FIG. 2;

FIG. 4 is a partial side elevation, similar to FIG. 1; of an alternativeform of the invention; and

FIG. 5 is a cross section of an outer hull which may be employed in anyof the previous figures.

Referring to the drawing, the subject of the invention comprises atorpedo hull 10 of any desired configuration, exemplary of which, asshown in FIG. 1, is a substantially elliptical hull, the major axis ofwhich is approximately eight times the minor axis with the tail portion11 modied to approximate a cone. As best shown in FIGS. '2 and 3 thehull comprises an inner imperforate portion 12 of any conventionaldesign which may withstand the pressure at a desired depth ofsubmergence and an outer portion 14 spaced from pressure hull 12 throughwhich Water may penetrate into annular space 16 disposed between the twoportions. As illustrated in FIGS. 1 to 3 outer hull portion 14 isprovided with axially spaced circular slots 18, the portions betweenslots being supported by the pressure hull by spaced webs 20.

The construction shown in FIG. 4 is essentially the same as that ofFIGS. l to 3 except that a plurality of spaced apertures 13A areprovided in outer hull 14A in lieu of the slots which thus permit theouter hull to be formed from a single sheet of perforate material ratherthan a plurality of axially spaced annular portions.

FIG. 5 illustrates another form of outer hull 14B in which a porousmaterial is employed for the outer hull through which water maypenetrate. An exemplary material is fiber glass batting, the linters orfibers of which are coated with an extremely thin coating ofthermoplastic resin, and then compressed under heat and pressure to bondthe fibers where they cross each other into a sheet of strong materialbut sufliciently porous to permit water to migrate through pores 18Bbetween the fibers or linters. In view of the ease of molding suchmaterial to desired configurations it is particularly advantageous foreconomical mass production.

The water penetrable material which may be either foraminous withdiscrete spaced apertures or porous with no discrete apertures permitswater from the boundary layer to enter into space 16 when a suction orpressure lower than ambient pressure is established within such space.To provide such suction a pump 22 is employed, exemplary of which is anaxial flow pump of the propeller type comprising one or more propellerblades 24 and angularly spaced stators 26 which provide more efiicientconditions for water entry into the propeller blades, such pumps beingwell known in the art. In addition to effecting ow of boundary Waterfrom the ambient layer into space 16, the propeller blades serve asecond function of directing the water axially rearwardly in a jet, thereaction of which provides the thrust for 4the torpedo. Preferably, thewater is accelerated through a restricting nozzle 2S to increase itsdynamic head which, in general, provides increased thrust eliiciency.

The pressure drop across the outer hull should be sufficient to preventoutward ow of water at all speeds and angles of attack. If the internalpressure is to be constant at all points then the hull should preferablybe so designed to have uniform pressure distribution on its outersurface. If uniform pressure distribution cannot be effected by aparticular desired design then the internal pressure may be variable, byemploying manifolding or compartmenting (not shown), to produce uniformpressure drop across the various portions of the hull with variablepressure distribution on the outer surface of the hull. A pressure dropof- 4 to 8 p.s.i. will, in general, be found adequate.

Some clogging of the penetrableV material may be eX- pected since seawater will normally contain particles which will not pass through thematerial. While it might appear that such clogging would reduce the rateof ow of water through the penetrable shell and thus adversely affectthe performance characteristics of the torpedo such action will notoccur since the tendency to increase suction head of the pump due toclogging distributes a greater portion of the applied pump power tocreating increased suction head, thereby maintaining iiow rate constant.While this decreases the distribution of the power applied to thedischarged Water, the decrease in propulsion performance is slight sincea very substantial portion of the power is utilized for propulsion andonly the minor remainder employed for suction.

Suction of water through a permeable hull tends to control the boundarylayer to maintain its flow laminar; however, disturbances, such ascaused by surface roughness or hull shape may offset such tendency. Thusin FIG. 2A, there may be laminar low 30 adjacent hull 14 along a portionof its length after which surface roughness may change it to a disturbedlaminar flow as indicated by 32. Continued flow along the hull may causefurther disturbance until it changes to turbulent ow 34. When thisoccurs, uniform suction through the hull adjacent the turbulent zonewill not change the turbulent flow back to laminar flow. It has beenfound, however, that the disturbance in the laminar flow may be nulliedif a high rate of inward tloW is effected at a localized zone and beforeturbulence occurs. Thus in FIG. 2B, one of the apertures 18 adjacent thebeginning of disturbed laminar flow 32 is considerably enlarged in area,as indicated at 153C, so that the rate of flow 36A is considerablyincreased over the ow 36 through the smaller apertures` 18. Thisnulliiies the disturbance and the water again flows laminar until afurther disturbance occurs further rearwardly of the hull. As will beapparent, a plurality of apertures 13C may be disposed in axially spacedrelation along the hull.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that Within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. A torpedo comprising;

(a) an elongated hull,

(b) the major portion of the length of said hull being of waterpenetrable material adapted to permit ow of water from the boundarylayer through said hull into a space therewithin,

(c) a pump adapted to discharge a jet of water rearwardly from thetorpedo, said jet providing the sole source of thrust for propellingsame,

(d) said pump communicating with said space for providing suction topro-duce said flow,

(e) a major portion of the power applied to the pump being utilized forpropulsion of the torpedo and a minor portion for producing saidsuction,

(f) whereby as said material tends to clog with foreign matter, saidpump tends to maintain said ow substantially constant withoutsubstantial decrease in the propulsion etect of said jet.

2. A torpedo comprising;

(a) an elongated hull having circumferential sets of apertures disposedin laxially spaced relation along a substantial portion of its lengthand extending therethrough and communicating with a space therewithin,

(b) certain of said sets of apertures being of greater cross-sectionalarea than other of said sets, whereby the rate of flow of watertherethrough is greater than through the other of said sets,

(c) the sets of apertures having the greater cross sectional area beingdisposed at positions along the length of the torpedo at which thelaminar flow tends to change to disturbed laminar flow, to therebyprevent turbulent flow and etect continued laminar tlow acrossrearwardly disposed apertures,

(d) means for maintaining a substantially uniform suction pressurewithin said space to thereby produce greater ow through the sets ofapertures of greater cross section than through the other sets ofapertures, and

(e) means for discharging the water entering said space through the rearend of the torpedo.

References Cited hy the Examiner UNTTED STATES PATENTS 2,147,550 2/39Sabathe 114-20 2,382,593 8/45 Wires 114-20 2,742,247 4/56 Lachmann244-130 2,969,759 1/61 Giles 114-20 3,066,893 12/62 Mercier 114-20FOREIGN PATENTS 717,416 10/54 Great Britain. 272,707 3/ 30 Italy.

BENJAMN A. BORCHELT, Primary Examiner.

1. A TORPEDO COMPRISING; (A) AN ELONGATED HULL, (B) THE MAJOR PORTION OFTHE LENGTH OF SAID HULL BEING OF WATER PENETRABLE MATERIAL ADAPTED TOPERMIT FLOW OF WATER FROM THE BOUNDARY LAYER THROUGH SAID HULL INTO ASPACE THEREWITHIN, (C) A PUMP ADAPTED TO DISCHARGE A JET OF WATERREARWARDLY FROM THE TORPEDO, SAID JET PROVIDING THE SOLE SOURCE OFTHRUST FOR PROPELLING SAME, (D) SAID PUMP COMMUNICATING WITH SAID SPACEFOR PROVIDING SUCTION TO PRODUCE SAID FLOW, (E) A MAJOR PORTION OF THEPOWER APPLIED TO THE PUMP BEING UTILIZED FOR PROPULSION OF THE TORPEDOAND A MINOR PORTION FOR PRODUCING SAID SUCTION, (F) WHEREBY AS SAIDMATERIAL TENDS TO CLOG WITH FOREIGN MATTER, SAID PUMP TENDS TO MAINTAINSAID FLOW SUBSTANTIALLY CONSTANT WITHOUT SUBSTANTIAL DECREASE IN THEPROPULSION EFFECT OF SAID JET.